题目描述

blablabla

样例

#include<iostream>
#include<vector>

using namespace std;

bool cmp(vector <int>&A,vector<int>&B) {
    if(A.size()!=B.size())
        return A.size()>B.size();

    for(int i=A.size()-1; i>=0; i--)
        if(A[i]!=B[i])
                return A[i]>B[i];

                return true;
    }
vector<int> sub(vector <int>&A,vector<int>&B) {
    vector <int>C;
    for(int i=0,t=0; i<A.size(); i++) {
        t=A[i]-t;  //借位
        if(i<B.size())
            t-=B[i];
        C.push_back((t+10)%10);
        if(t<0) t=1; 
        else  t=0;
    }
    while(C.size()>1&&C.back()==0)   C.pop_back(); 
    return C;
}

int main() {
    string a,b;
    cin>>a>>b;
    vector<int> A,B;
    for(int i=a.size()-1; i>=0; i--)  A.push_back(a[i]-'0');
    for(int i=b.size()-1; i>=0; i--)  B.push_back(b[i]-'0');
    if(cmp(A,B)) {
    auto C=sub(A,B);
        for(int i=C.size()-1; i>=0; i--)
            printf("%d",C[i]);
    } else {
        printf("-");
        auto C=sub(B,A);
        for(int i=C.size()-1; i>=0; i--)
            printf("%d",C[i]);
    }
}